air leak = soft seize?

• Author: Andy (---.hsd1.ca.comcast.net)
• Verified User: akpasta
• Date Posted: 05-14-08 14:08

Running a 1980 Peugeot 103, sha 15.15, de-restricted exhaust, 57 jet (plug looks great). Just replaced condenser and ignition coil, and pulled out the rectifier, which seemed to be giving me weird electrical problems, also cut brake light cables from handlebars to minimize complications.

Crusing down the road 3-4 miles WOT the whole way (about 35mph), the piston locks up and the bike revs down really weird and won’t start again (but the cylinder moves). Took it home, opened the cylinder and it’s got a fair amount of scoring, nothing too deep; it was a little chalky and black, so I’m pretty sure it was a soft seize.

I wasn’t running with a base gasket, although I fixed that now with some high-density gasket paper. Don’t think I’ve got an intake leak, did the carb-cleaner spray test at idle to see if it would die. There’s a little drip of oil at the bottom of my crank case, but I don’t know where it’s dripping from, maybe a crank case leak?

Would light scoring along the piston cause a soft-seize? The bike starts fine now and runs with good compression, I don’t know what will happen when everything gets really hot again.